Tubular hollow organs bend as a result of pathological changes, which sometimes leads to occlusion or stenosis; such organs must be made passable once again. Various procedures are used for re-channelization, for example laser application, curettage, or the insertion of prostheses, which can be tubular for example and are then called stents. Problems often arise in the application of these stents, because the areas affected by stenosis lie very deep within the hollow organs, or else the organs have already become very severely deformed. Additional problems can arise due to the fact that a variety of sizes of these stents must be used, corresponding to the size of the hollow organ, and therefore the appropriate set of instruments must be available each time. Furthermore, it can become necessary to use an optic or to dispense gases or liquids during the positioning of the stent. Instruments are known for the application of such prostheses in a wide variety of forms, for example, from the following documents: U.S. Pat. No. 4,732,152; U.S. Pat. Nos. 4,848,343; 4,875,480; 4,533,545; 4,771,773; DE-OS 35 18 238; DE-OS 37 04 094; DE-OS 36 40 745; and DE-OS 33 22 001.
In addition, instruments are also known that are either provided with a balloon for the expansion of the hollow organ and setting a stent or are configured as a tube without additional spreading elements. While with balloons it is often disadvantageous that they are very easily deformable and are generally less suited to the application of tubular stents, tubular instruments make necessary the use of additional instruments, such as forceps and the like for application of the stent. An extraction of stents is not possible with these instruments.
From EP-A1 0 364 420 another instrument is known with which it is possible to transluminally implant or extract an essentially tubular and radially expandable stent. With this instrument the object of being able to exactly place and, equally exactly, to extract a stent is solved, whereby both procedures can be performed under observation through use of an optic. This instrument comprises essentially of an inner tube which is surrounded by a second tube that can be moved relative to the inner tube. In addition, a number of spreading elements are arranged on the inner tube, by means of which a stent can be held on the instrument and can be brought to the site of the application. When the outer tube is pushed back, the stent is brought under the influence of the spreading elements, which protrude radially outward. By means of a forward push on the outer tube, the spreading elements are pressed radially inward, whereby the stent is held firmly by the spreading elements between the inner and outer tubes. Then, under observation with the aid of an optic, the stent is brought to the site of treatment and is placed there when the above-described procedure for gripping the stent is carried out in reverse. Finally, the instrument is again withdrawn from the body cavity. With this instrument the space between the inner and outer tubes can also be used to introduce a liquid into the body cavity in order to rinse the distal end of the endoscope optic for a better view. In the same way, stents can be removed with this instrument under observation, whereby the operation described above is carried out in reverse order.
This instrument does not include any means of its own for the illumination of the body cavity, and can therefore be used only in conjunction with an endoscope, for example, a bronchoscope. This instrument also has the serious disadvantage that the free ends of the spreading elements can stick in the surrounding tissue, which can lead to serious injury to the hollow organ, for example, during bronchoscopy of the trachea and bronchial tubes. The fact that the stent cannot be applied correctly for some uses turns out to be an additional disadvantage. Similar problems also arise for instruments such as those disclosed in DE-G 92 07 941.
It is an object of the invention to provide an instrument with which stents can be correctly placed in a simple manner into tubular, hollow organs of various sizes, and just as easily removed from the body cavity again, and specifically, in such a way that any damage to the surrounding tissue that is caused by the mechanism for application of the stent is avoided, and that in addition, the otherwise common endoscopic treatments of hollow organs with auxiliary instruments and rinsing fluids can be carried out as well.